An Igusa CM invariant is specified by a sequence of three polynomials
[ H1(x), G2(x)/N2, G3(x)/N3],
such that
H1(x), G2(x), and G3(x) are in Z[x],
H1(i1) = 0, |
i2 = G2(i1)/N1N2, |
i3 = G3(i1)/N1N3, |
where N1 = H1'(i1),
and N2 and N3 are integers, and
i1 = I4I6/I10, |
i2 = I23I4/I10, |
i3 = I22I6/I10,
|
in terms of the Igusa-Clebsch invariants
[
I2,
I4,
I6,
I10
].
Degree 13 Igusa CM invariants of cyclic (C4) fields: 5
Number |
Igusa invariants |
Conductor |
Components |
Quartic invariants |
Class number |
Class group |
1) |
[317, 317, 15533] |
[1] |
1 |
[317, 317, 15533] |
13 |
C13 |
2) |
[269, 269, 6725] |
[1] |
1 |
[269, 269, 6725] |
13 |
C13 |
3) |
[509, 509, 61589] |
[1] |
1 |
[509, 509, 61589] |
13 |
C13 |
4) |
[397, 397, 3573] |
[1] |
1 |
[397, 397, 3573] |
13 |
C13 |
5) |
[557, 557, 27293] |
[1] |
1 |
[557, 557, 27293] |
13 |
C13 |